The invention discloses a method for synthesizing medium-chain triglyceride fatty acid in a raw material medicine. The method comprises the following synthesis steps: preparing materials, namely mixing glycerinum with fatty acid in a mass ratio of 1:(5-7) under a vacuum room temperature condition of minus 0.090MPa; performing esterification reaction, namely slowly heating the mixed material to 150-245 DEG C for 50-70 minutes in an esterification reactor, gradually adjusting the pressure to be lower than or equal to minus 0.020MPa along with increase of the temperature, and keeping the temperature for 120-420 minutes at the esterification temperature of 150-245 DEG C; and performing fatty acid desorption, namely after the esterification reaction is completed, removing residual fatty acid at vacuum of lower than or equal to 0.090MPa for 30-120 minutes. The method adopts a catalyst-free esterification technique, so that use security of the medicinal medium-chain triglyceride fatty acid is improved, and good product appearance is ensured. By adopting the method, domestication of the medium-chain triglyceride fatty acid is achieved, and the medium-chain triglyceride fatty acid is not imported any longer and is used in match with medicinal soybean oil.